Reinduction (weeks 20-29): Patients receive oral dexamethasone three times daily on days 134-154; vincristine IV on days 141 and 148; doxorubicin IV over 15 minutes on days 134, 141, 148, and 155; and asparaginase IM on days 141, 144, 148, 151, 154, and 157. Beginning on day 169 or when blood counts recover, patients receive cyclophosphamide IV on day 169, cytarabine IV over 72 hours on days 171-173 and 178-180; oral thioguanine daily on days 169-182; and methotrexate IT on days 171 and 178. Patients also receive cranial irradiation for up to 10 days beginning on day 189.